Lubricating oils



atented Mar. 23, 1937 LUBRICATIN G OILS Bert H. Lincoln, and AlfredHenriksen, Ponca City, Okla., assignors, by mesne assignments, to TheLubri-Zol Development Corporation, Cleveland, Ohio, 'acorporation ofDelaware No Drawing. Application May 12, 1932, Serial 12 Claims.

This invention relates to an improvement in lubricating oils, and moreparticularly to an oil of increased lubricity.

Under conditions of boundary lubrication the viscosity of the lubricantplays only a minor part in lubrication. With slow speeds and heavy loadscontributing to boundary lubrication, the lubricant to be emcient musthave a high degree of oiliness or unctuosity and must have a high film10 strength. The very best mineral oils are, as a rule, very deficientin oiliness character and film strength, resulting in considerable wear,low eificiency, and at times seizure of metals in machines lubricatedwith mineral oils only. For these particular duties lubricatingengineershave used animal and vegetable oils with some success, but the changesoccurring in the animal and vegetable oils during use have made themvery unsatisfactory for general use, as well as uneconomical due to theexpense of the fatty oils and the quantities required.

Mineral oils having low film strength. allow seizure of therubbingsurfaces when, for one reason or another, pressures are increased or therubbing speed is slow. 7

Objects of this invention are to provide a lubricant with high oilinesscharacter and high film strength without introducing the objectionablefeatures of lubricating oil sludging, gumming, rancid odor andperceptible corrosion. The application of this invention realizes theseobjects very economically. f

It has been found that commercial stearic acid as found on the marketand other saturated fatty acids, when blended with mineral lubricatingoil, will greatly reduce the coefficient of friction. As an example, agood grade mineral oil had a coefficient of friction of 0.135 to 0.140when tested on the Herschel friction testing machine with a 40% 'leaddisc. (The Herschel friction testing machine is a development by Dr. W.H. Herschel of the U. S. Bureau of Standards) When 0.5% commercialstearic acid was added to the above mineral oil, it had a coefficient offriction of only 0.055. Thus, by adding a very small amount of stearicacid, the coeflicient of friction was only 39 to 41% as great aswith theoriginal oil.

. The melting point of commercial stearic acid is around 100-170" F.,depending upon the impurities present in the commercial acid. (Theseimpurities do not affect the value of this invention, it being foundthat any'ofthe commercial stearic acids are suitable.) Stearic acid iscompletely soluble in mineral oil at high temperatures, but due to itshigh melting point, the stearic acid starts solidifying as thetemperature goes below say 100 F. and at low temperatures, say around 15to 30 F., will in time settle out of the solution. This is acommon'characterlstic of the requires their use in warm weather andprohibits storage and use of lubricants prepared in this manner duringcold weather. With this knowledge, the use of saturated fatty acids inmineral oil may be economically and eificlently applied in a number ofplaces.

It has been found, however, that the solubility and film strength offatty acids can be greatlyimproved by halogenation. The halogenatedfatty acids will remain in solution over long time storage during coldweather and will not cause sludging of the lubricant, gumming or .otherobjectionable features. Addition of halogen to the fatty acid moleculelowers the melting point and accomplishes this very beneficial resultand makes them available for economical use under any kind. oftemperature conditions.

As an example of this, ordinary commercial stearic acid (a saturatedacid) with a melting point around 120-140 F. was chlorinated direct withchlorine until the chlorinated product had a melting point of 62 F.Excess free chlorine and hydrochloric acid are removed by any of theordinary means and the chlorinated product added to mineral oillubricants in small quantities. The poorer the quality of the originallubricating oil the more the chlorinated acid required. The Herschelfriction testing machine was used to determine the increased oiliness.The original mineral oil showed a coeflicient of friction of 0.135 to0.140%. Chlorinated stearic acid was added in quantities of from .05% to.5% with the following results:

Amt. of chlor. stearic Coefficient of friction acid added to minonHerschel friction eral lubricant machine Original mineral lubricant0.135 to 0.140

.05% 0.072 to 0.077 .l% 0.070 to 0.075 .25 o 0.070 to 0.075 .50% 0.070to 0.075

Another sample of commercial stearic acid was chlorinated until thechlor acid had a. melting point of 9 F. This product was added to thesame mineral oil with the following results:

Amt. oi chlor. stearic coem i cient of frictiongfgfiggfgfig mm onHerschel machine Original mineral lubricant 0.135 1:00.140 0.05% 0.075to 0.080 0.10% 0.075 to 0.080 0.25% 0.075 to 0.080 0.5% 0.115 to 0.120

I Both of the above examples clearly show that I saturated fatty acidsofhigh melting point, which the maximum reduction in coeflicient'offriction is obtained with small quantities 'of the chlor fatty acid. Inthe case of the fatty acid chlorinated to 9 F. melting point, thecoefficient of friction increased when the amount of acid added reached0.5%. As previously stated, with a poorer quality original mineral oilas much as 2% or more acid may be required to get thesame reduction incoefllcient of friction.

Commercial oleic acid representing the field of unsaturated fatty acidswas chlorinated to partial saturation and suflicient chlorine added toprevent acid sludging or polymerization of the unsaturated acid. Thisproduct, when added to a mineral lubricant having an-originalcoefficient of friction of 0.135 to 0.140, gave the following result.

' Coefllcient oi friction W? Herschel machine 0.5%" Original mineral oil0.135 to 0.140

. It has been found that unsaturated free fatty acids will reduce thecoeiflcient of friction when used in small quantities. For example, 0.5%of oleic acid in a mineral oil having an original ooeillcient offriction of 0.135 to 0.140 gave a prodarea of rubbing surfaces underconditions resembling those found in commercial use but probably alittle more severe. The lubricant is placed between the frictionsurfaces and used with increasing pressure or load at the friction pointuntil seizure of the metal surfaces occurs. With the Mougey machine thepressure or load may be held constant and determine the time requiredfor seizure of the metal surfaces. By the use of these machines it iseasy to compare the film strength of two oils. I

Using the Mougey machine a good grade mineral oil allowed seizure of thefriction surfaces in 30 minutes with a load of 2000# per square inch.

5 Using another sample of the same mineral oil blended with 0.5% ofchlorstearic acid of 9 F.

melting point and operating the Mougey machine at 2000 pounds .persquare inch pressure, there were no signs of seizure after a period of45 min- 60 utes, proving a decided superiority of film strength in thelubricant blended with chlorstearic acid. With higher pressures, largerquantities of the chlorstearic acid should be used-as much as 5% or morebeing required.

Using the timken machine with the original lubricant seizure of metalsurfaces occurred when 18.2# .weights had been added, which represent apressure 'of approximately 10,500 pounds per square inch. To a sample ofthis'same lubricant 0.25% of chlorstearlc acid of 9 1". cold test'wasadded, and when this blended lubricant was used in the Timlren machineseizure did not occur until a 32.2# weight had been added representing apressure of approximately 19,000 pounds per square inch.

machines is to give very high pressure per. unit Repeating the testonthe Timken machine with the same original lubricant containing 0.5% ofchlorstearic acid-of 9 F. melting point, metal seizure did not occuruntil 88.0 pound weights had been added, which represents a pressure ofapproximately 22,000 pounds per square inch. Thus, by adding 0.5% of theproduct of this invention to a high quality lubricant, its film strengthismore than doubled.

The above tests clearly demonstrate the economy and efficiency of theprocess and show that by this invention it is possible to prepare alubricant for practically any duty by either varying the percentageofproductblended and/or varying the degree of halogenation of the productto be blended.

It has also been found that lubricants prepared by this invention do notlose their oiliness characteristics when diluted with small amounts ofunburned motor fuel, making this type of lubricant of unusual value inactual commercial lubrircation conditions.

The addition of halogenated fatty acids in the manner of our inventionreduces sludglng or polymerization in the oil. For example, using theTidewater oxidation test, which consists in determining the amount ofsludge formed in an all after heating for seven hours at 392 F..-thefollowing results were obtained:

300 reduced oil 0.5% oleic acid gave a sludging number of 91.6 while thesame 011 with 0.5% of halogenated oleic acid gave a sludglng number of72.4 or a reduction in sluding number of 19.2. Having thus described ourinvention, what we claim is:

1. A lubricant comprising in combination a mineral oil and a'smallpercentage of a halogenated higher fatty acid of the aliphatic series.

2. A lubricant comprising in combination a mineral oil and a smallpercentage of a chlorinated higher fatty acid of the aliphatic series.

3. A lubricant comprising in combination a mineral oil and a smallpercentage of halogenated stearic acid.

4. A lubricant comprising in combination a mineral oil and a smallpercentage of halogenated oleic acid. I

5. A lubricant comprising in combination a mineral oil and a smallpercentage of chlorinated stearic acid. r

6. A lubricant comprising in combination a mineral oil and a smallpercentage of chlorinated oleic acid. a

7. A lubricant comprising in combination a mineral oil and a smallpercentage of a halogenated unsaturated fatty acid.

'8. A lubricant comprising .in combination a mineral oil and a smallpercentage of a halogenated saturated fatty acid. 9. A lubricantcomprising in combination a mineral oil and a small percentage of a halogenated acyclic, monocarboxylic acid.

10. A lubricant comprising in combination a mineral oil and a smallpercentage of a chicrinated acyclic monocarboxylic acid. 11. A lubricantcomprising in combination a mineral oil and'a small percentage of ahalogenated acid of the acrylic series.

- 12. A lubricant comprising in combination a mineral oil anda smallpercentage of a chlorinated acid of the acrylic series.

